You have nothing to be nervous of , you are female , therefore you have the cards stacked in your favour. Most guys will be highly appreciative of a woman that gives them the time of day , as this rarely happens , remember a lot of women are quite brutal towards guys that they aren't attracted to / does not like the guys approach. Guys NEVER shoot girls down , remember this & relax & enjoy yourself , put yourself at ease.

It's most likely the same reason some guys find it hard to talk to girls.. shyness and awkwardness :D. Also, not all guys are hard to talk too, you've just got to go and initiate conversation, and you'll be chatting comfortably in no time XD.